“They aren’t concerned at all,” the person says on tape. “They are happy to have a party when black people drown.”

That line elicits laughter from several employees listening in on the joke.
http://newsbusters.org/blogs/matthew-sheffield/2012/08/29/abc-news-romneys-happy-have-party-when-black-people-drown#ixzz24wrPQP1x

Video is here, at about 5-6 seconds into the tape: